The present invention is in the field of devices for use in surgical procedures. More particularly, the present invention relates to a device having both a venous blood reservoir and a cardiotomy reservoir for use in an extracorporeal circuit.
Many surgical operations involve circulating the blood of a patient through an extracorporeal circuit. In particular, many open-heart surgical procedures require that the patient""s heart be stopped, and that various biological functions (i.e., blood circulation and oxygenation) be performed mechanically by various devices included in the extracorporeal circuit. In addition to a pump and to the tubing through which the blood will flow, devices including oxygenators, heat exchangers, and blood accumulation reservoirs may be employed. Each of these devices is monitored and managed by persons who may be present in the operating room, or at remote monitoring and control stations.
One type of blood accumulation reservoir used in such procedures is a venous reservoir. The venous reservoir serves as a receptacle for blood, typically blood that has been removed from the patient through a vein, which is subsequently oxygenated and further processed prior to being recirculated back to the patient. Thus, the venous reservoir typically serves to collect blood as it first enters the extracorporeal circuit. The use of the venous reservoir enables the operator to control the blood flow rate, blood pressure, blood volume and related parameters necessary to maintaining the patient during the surgical procedure.
A second type of blood accumulation reservoir used in such procedures is a cardiotomy reservoir. The cardiotomy reservoir is used to contain blood which has been collected from the operating field. Blood collected in the cardiotomy reservoir can be reinfused into the patient after being filtered to remove any clots or other unwanted contaminants.
Since the space in the operating room available to operators is often limited, devices have been proposed which combine the venous reservoir and the cardiotomy reservoir in a single structure. In such devices, inlets for the venous blood and for the blood from the operating field are separated from one another. Blood entering the device is filtered and then collected in a common chamber.
These devices, however, are known to have certain disadvantages. For example, the surface area of such devices which comes into contact with the blood is relatively large. As a result, the blood becomes susceptible to damage or coagulation. Additionally, even under relatively normal operating conditions, retrograde blood flow may be induced, causing the blood to be reverse filtered. This is particularly problematic if only venous blood is being collected, because the retrograde flow causes the blood to be sequestered within the cardiotomy filter, thereby reducing the volume of blood available for oxygenation and recirculation to the patient.
One object of the present invention is to provide a combined device having both a venous blood reservoir and a cardiotomy reservoir. Another object of the invention is to provide a device which allows venous blood and cardiotomy blood to be optionally integrated if surgical conditions or requirements warrant. Still another object of the invention is to provide a combined venous blood reservoir and cardiotomy reservoir which minimize blood contact with large surface areas of the device and which eliminate the risk of reverse filtration.
These and other objects of the invention are achieved by a combined device having a venous blood reservoir and a cardiotomy reservoir. The device is characterized in that it includes a housing having a partition which separates a lower reservoir from an upper reservoir. The lower reservoir is adapted for use as the venous reservoir, and the upper reservoir is adapted for use as the cardiotomy reservoir. The venous reservoir is provided with a blood inlet connector and a blood outlet connector, and the cardiotomy reservoir and is provided with a blood inlet connector and with an air outlet connector. Each of the blood inlet connectors is positioned so that blood entering the device is caused to flow through a defoaming substance and a filter. Additionally, the partition which separates the venous reservoir from the cardiotomy reservoir is provided with at least two ducts which, starting from apertures formed in the partition, project upward into the cardiotomy reservoir and reach different elevations therein.